A developer focused on a single story during an entire sprint.

The Scrum team should break the stories into workable items that can be completed within one sprint, which is a time-boxed period of 7 to 30 days, during which the team delivers a potentially releasable product increment. Breaking the stories into smaller and more manageable items can help the team to estimate them more accurately, plan them more effectively, and deliver them more reliably. Breaking the stories also aligns with the agile principle of delivering working software frequently and satisfying the customer through early and continuous delivery of valuable software.

The other options are not the best steps for the Scrum team to take next. Assigning more resources to complete similar stories in the future may not solve the problem of underestimation, and may introduce additional complexity and communication overhead. Extending the sprint duration when required with the approval of the product owner may compromise the consistency and predictability of the Scrum process, and may delay the feedback and validation from the stakeholders. Releasing the current progress into production and carrying over the rest of the code for the next sprint may result in an incomplete or unstable product increment, and may violate the definition of done, which is a shared understanding of the quality criteria that the product increment must meet. References = CompTIA Project+ Study Guide: Exam PK0-005, 3rd Edition, Chapter 5: Project Scope Management1; CompTIA Project+ Certification Study Guide, 3rd Edition, Chapter 5: Project Scope Management2; The 3 Scrum Roles and Responsibilities Explained3; Implementation of Scrum - 7 Steps for an Effective Process4